This invention relates to tufting machines and more particularly to the feeding of base material to a controlled needle tufting machine for performing overtufting operations.
Controlled needle tufting machines are known which operate to skip stitch in accordance with a program for forming tufted designs in a backing fabric. Basically these machines render selective needles or groups of needles inoperative while the remainder of the needles are operative to pierce the backing fabric upon each stroke of the needle bar. Examples of this type of machine are illustrated in U.S. Pat. Nos. 3,115,856; 3,259,088 and 3,881,432.
Overtufting is a process wherein a fabric previously formed with tufted pile fabric is then tufted to insert additional pile, such additional pile being stitched at predetermined locations in the base material and primary or base pile. Overtufting with yarn of different colors than the primary pile provides desirable and appealing patterning effects in the fabric, especially carpeting.
In the production of carpeting in this manner the base material with the primary pile is fed over the needle plate of the tufting machine with the primary pile projecting downwardly toward the loopers or hooks which cooperate with the needles carrying the overtuft or secondary yarn.
Conventionally, the feeding of the base material through a tufting machine occurs through a plurality of feed rollers and take-up rollers. When base material is fed to the tufting instrumentalities, e.g., the needles and hooks, the base material is guided and fed between a pair of rollers. One of the rollers, known as a picker roll because it has a multiplicity of picks, or spikes or pins, extending from the surface thereof, engages and grasps the base material. As illustrated in U.S. Pat. No. 3,986,465, it is known in the prior art to utilize a picker roll between a pair of smooth surface rollers at the take-up portion of the feed system downstream of the tufting instrumentalities, but in regard to the rolls feeding material toward the tufting instrumentalities the picker roll is disposed beneath the base material, i.e., the lower surface of the base material is guided over and engages the picker roll. This has been the case whether the tufting machine is conventional or is an overtuft controlled needle machine. Although such feeding creates no significant problems when overtufting a low density fabric, it is now been found that when high density (or fine gauge) fabrics are to be overtufted, the picker rolls tend to pull the primary pile from the base material with the result that the carpet produced has snags and loose yarn ends.